TestOut LabSim A+ Certification Practice Exam

How do switches and bridges learn where devices are located on a network?

1. By polling devices at regular intervals.

2. When a frame enters a port, the destination MAC address is logged.

3. When a frame enters a port, the source MAC address is copied from the frame header.

4. Through built-in algorithms based on traffic patterns.

The correct answer is: When a frame enters a port, the source MAC address is copied from the frame header.

Switches and bridges learn the locations of devices on a network primarily by copying the source MAC address from incoming frames. When a frame is received on a port, the device examines the frame header, which includes the source MAC address. By recording this address alongside the port the frame was received on, the switch or bridge builds a MAC address table. This dynamic mapping allows it to effectively forward frames to their intended destination by referring to the table, ensuring efficient data transmission across the network. This method is efficient because it allows the device to update its knowledge of the network as new devices are introduced or as existing devices change location. The process does not depend on polling devices or relying on traffic patterns; rather, it works by directly observing the communications on the network, which is a hallmark of how Ethernet switches operate.